net: check extack._msg before print

dev_set_mtu_ext is able to fail with a valid mtu value, at that
condition, extack._msg is not set and random since it is in stack,
then kernel will crash when print it.

Fixes: 7a4c53bee3 ("net: report invalid mtu value via netlink extack")
Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Li RongQing 2018-08-03 15:45:21 +08:00 committed by David S. Miller
parent 0ed4229b08
commit a6bcfc8969

View file

@ -7583,8 +7583,9 @@ int dev_set_mtu(struct net_device *dev, int new_mtu)
struct netlink_ext_ack extack;
int err;
memset(&extack, 0, sizeof(extack));
err = dev_set_mtu_ext(dev, new_mtu, &extack);
if (err)
if (err && extack._msg)
net_err_ratelimited("%s: %s\n", dev->name, extack._msg);
return err;
}